1. Field of the Invention
This invention relates to the method of making urea-formaldehyde polymers which have reduced aldehyde vapor emissions, to a method of making a cellular urea-formaldehyde foam with reduced aldehyde emissions and to a urea-formaldehyde foam having reduced aldehyde emissions.
2. Prior Art Relating to the Disclosure
The emission of formaldehyde vapor from particle-board, plywood and insulating foams and other such materials made with or incorporating urea-formaldehyde resins, is and continues to be a problem. Numerous methods have been proposed to reduce the free formaldehyde content of urea-formaldehyde resins. U.S. Pat. No. 4,129,533 discloses substitution for 20 percent of the total aldehyde moieties of the urea-formaldehyde resin, one or more aryl dialdehydes having two to eight carbon atoms, the dialdehydes provided as a cross-linking solution at the time of final polymer formation. The patent also mentions the use of large amounts of calcium lignosulfonates and mineral oil containing sodium silicate for reducing the aldehyde emission of urea-formaldehyde resins. U.S. Pat. No. 3,979,341 discloses the use of furfuryl alcohol and resorcinol to reduce formaldehyde odor in urea-formaldehyde foams. U.S. Pat. No. 3,231,525 discloses preparation of urea-formaldehyde foams in which the formaldehyde odor is substantially suppressed or eliminated by adding free urea to the hardner solution during manufacture of the foam.